The micromixing of two fluids plays a vital role in lab-on-a-chip devices. For obtaining better mixing efficiency, we propose a micromixer using patchwise surface potential heterogeneity and wavy wall. We numerically investigate the hydrodynamic and mixing characteristics for flow through a microchannel with a straight top wall and wavy bottom wall. The primary flow is actuated by an external pressure-gradient and patches are placed at the top wall with positive zeta potential, such that the reversed electroosmotic actuation forms the recirculation zones close to the top wall. The streamlines, flow velocity, recirculation zone velocity, species concentration, flow rate, and mixing efficiency are investigated by varying the relative pressure-gradient strength, Debye parameter, zeta potential and wavy surface amplitude. Two different configurations are considered by placing the patches at the top wall, opposite to the peaks and valleys of the bottom wavy surface, respectively. It reveals that the recirculation zone velocity increases with the increase in both Debye parameter and surface amplitude, whereas it decreases with relative pressure-gradient strength near the patch surfaces. The flow rate decreases with the increase in zeta potential and we also identify the values of zeta potential for chocking of flow in the microchannel. It reveals that the mixing efficiency monotonically increases with surface amplitude, and the variation with zeta potential is non-monotonic. We also identify the range of zeta potential for which the value of mixing efficiency is higher than 90% for different configurations of the channel.

两种流体的微混合在芯片实验室设备中起着至关重要的作用。为了获得更好的混合效率，我们提出了一种使用贴片表面电位异质性和波浪形壁的微混合器。我们数值研究了流体通过具有直顶壁和波浪形底壁的微通道的流体动力学和混合特性。初级流由外部压力梯度驱动，贴片放置在具有正 zeta 电位的顶壁，使得反向电渗驱动形成靠近顶壁的再循环区。通过改变相对压力梯度强度、德拜参数、zeta 电位和波状表面振幅来研究流线、流速、再循环区速度、物质浓度、流速和混合效率。通过将贴片放置在顶壁，分别与底部波浪形表面的波峰和波谷相对，可以考虑两种不同的配置。结果表明，再循环区速度随着德拜参数和表面振幅的增加而增加，而随着贴片表面附近的相对压力梯度强度而减小。流速随着 zeta 电位的增加而降低，我们还确定了 zeta 电位值用于阻塞微通道中的流动。结果表明，混合效率随表面振幅单调增加，而随zeta电位的变化是非单调的。我们还确定了对于不同通道配置的混合效率值高于 90% 的 zeta 电位范围。